Vehicle wheel bearings are disposed around the vehicle axles and include a plurality of rollers or bearings to permit relatively frictionless rotation of wheels about the axles. Periodically, these rollers must be lubricated with a very viscous lubricant, commonly called wheel-bearing grease. Wheel bearings generally include an inner, or axle contacting, cylindrical member and a concentric, outer cylindrical member of large diameter, which is spaced apart from, and connected to the inner cylindrical member by virtue of a plurality of intermediate rollers or bearings. The rollers or bearings protrude, both below and above the outer cylindrical portion of the wheel bearing so that an innermost periphery of the bearings contact the outer surface of the axle contacting portion of the wheel bearing, and so that the outermost periphery of the bearings are adapted to contact an inner portion of the wheel for rotating movement. The space provided by the rollers or bearings between the inner cylindrical portion of the wheel bearing and the larger diameter outer cylindrical portion of the wheel bearing must be lubricated periodically in addition to lubricating the exposed portions of the rollers or bearings to provide for continuous rotation of these rollers or bearings during use. Accordingly, it is essential to inject wheel bearing grease between the inner and outer cylindrical wheel bearing members to provide for sufficient lubrication of the rollers during wheel rotation to prevent these rollers from freezing or locking up during vehicle movement. The space between the inner and outer cylindrical members of a wheel bearing is generally very narrow, on the order of 1/32 inch to 1/4 inch, and the injection of wheel bearing grease is further difficult because the rollers or bearings are disposed between the inner and outer cylindrical members, making the volume remaining for grease injection between the cylindrical members very small. Further, wheel bearing grease is very viscous, making it quite difficult to inject such material in small spaces.
Prior to the present invention, the most common way for greasing a wheel bearing has been to attempt to insert the grease by hand. Generally, the mechanic will locate a volume of grease in the palm of one hand and, taking the wheel bearing in the other hand, he will attempt to scoop the grease from his palm into the wheel bearing, and, in this manner, try to force the grease between the inner and outer cylindrical wheel bearing members. At the same time, the mechanic will apply grease over the outer exposed portions of the rollers and, by turning the rollers, will cause some grease to roll between the inner and outer cylindrical wheel bearing members. This method has been unsatisfactory because insufficient grease is forced within the wheel bearing necessitating periodic greasing and other wheel bearing maintenance.
Others have attempted to fabricate various devices for the purpose of inserting grease between wheel bearing components but these devices generally have been unsatisfactory because they are cumbersome, expensive and require far too much of a mechanic's time to grease a single wheel bearing. Further, many prior devices have required hydraulic force or other burdensome or expensive means for forcing the grease into the small cavities existing between wheel bearing rollers. Another drawback of prior art wheel bearing greasing devices has been, for example, that the wheel bearing being acted upon does not remain centered in the apparatus, resulting in uneven grease application around the circumference of the bearing, causing uneven bearing wear. Further, the inability of prior art devices to center the wheel bearing or maintain the wheel bearing centered during grease application has caused slippage of the wheel bearing, enabling some of the grease to circumvent the bearing, sometimes without notice by the mechanic.
In accordance with the present invention, a method and apparatus are provided for injecting grease or other viscous materials into contact with unexposed portions of wheel bearing rollers by providing a method and apparatus which is simple and inexpensive and can be used by any mechanic having access to a vice.